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[enh] fix issue 10965 - Allow alias initializer as enum member to avoid counter reset #2529

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[enh] fix issue 10965 - Allow alias initializer as enum member to avoid counter reset #2529

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12 changes: 9 additions & 3 deletions src/enum.c
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Original file line number Diff line number Diff line change
Expand Up @@ -280,6 +280,7 @@ void EnumDeclaration::semantic(Scope *sc)
}
else if (first)
{
Lfirst:
if (memtype)
t = memtype;
else
Expand All @@ -303,6 +304,9 @@ void EnumDeclaration::semantic(Scope *sc)
}
else
{
if (!elast)
goto Lfirst;

// Lazily evaluate enum.max
if (!emax)
{
Expand Down Expand Up @@ -336,7 +340,8 @@ void EnumDeclaration::semantic(Scope *sc)
error("enum member %s has inexact value, due to loss of precision", em->toChars());
}
}
elast = e;
if (!em->isAlias)
elast = e;
em->value = e;

// Add to symbol table only after evaluating 'value'
Expand Down Expand Up @@ -480,10 +485,11 @@ Dsymbol *EnumDeclaration::search(Loc loc, Identifier *ident, int flags)

/********************************* EnumMember ****************************/

EnumMember::EnumMember(Loc loc, Identifier *id, Expression *value, Type *type)
EnumMember::EnumMember(Loc loc, bool isAlias, Identifier *id, Expression *value, Type *type)
: Dsymbol(id)
{
this->ed = NULL;
this->isAlias = isAlias;
this->value = value;
this->type = type;
this->loc = loc;
Expand All @@ -508,7 +514,7 @@ Dsymbol *EnumMember::syntaxCopy(Dsymbol *s)
em->type = t;
}
else
em = new EnumMember(loc, ident, e, t);
em = new EnumMember(loc, isAlias, ident, e, t);
return em;
}

Expand Down
3 changes: 2 additions & 1 deletion src/enum.h
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Original file line number Diff line number Diff line change
Expand Up @@ -82,11 +82,12 @@ class EnumMember : public Dsymbol
{
public:
EnumDeclaration *ed;
bool isAlias;
Expression *value;
Type *type;
VarDeclaration *vd;

EnumMember(Loc loc, Identifier *id, Expression *value, Type *type);
EnumMember(Loc loc, bool isAlias, Identifier *id, Expression *value, Type *type);
Dsymbol *syntaxCopy(Dsymbol *s);
void toCBuffer(OutBuffer *buf, HdrGenState *hgs);
const char *kind();
Expand Down
3 changes: 2 additions & 1 deletion src/parse.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1630,6 +1630,7 @@ EnumDeclaration *Parser::parseEnum()

Type *type = NULL;
Identifier *ident;
bool isAlias = token.value == TOKalias ? nextToken(), true : false;
Token *tp = peek(&token);
if (token.value == TOKidentifier &&
(tp->value == TOKassign || tp->value == TOKcomma || tp->value == TOKrcurly))
Expand Down Expand Up @@ -1657,7 +1658,7 @@ EnumDeclaration *Parser::parseEnum()
error("if type, there must be an initializer");
}

EnumMember *em = new EnumMember(loc, ident, value, type);
EnumMember *em = new EnumMember(loc, isAlias, ident, value, type);
e->members->push(em);

if (token.value == TOKrcurly)
Expand Down
33 changes: 33 additions & 0 deletions test/compilable/test10965.d
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Original file line number Diff line number Diff line change
@@ -0,0 +1,33 @@
enum E1
{
alias a,
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That's a little more than what the enhancement request is about, it's also a very special case compared to what alias usually does, I think we shouldn't go this far.

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I was thinking about this, too. So initializers are needed for alias members?

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They're supposed to refer to existing members, e.g. alias b = a;.

Anyway, it's kind of fast to implement this already, since I've just filed the enhancement. Maybe a NG discussion should be made first to get a go-ahead.

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Well I've posted to the newsgroups. I don't have high hopes that it will be accepted. However Issue 9395 is something that can easily pass through. If you want to have a go at it, you might want to see Pull 463 for a reference.

b,
c = 2,
alias d = c,
e,
}

static assert(E1.a == 0);
static assert(E1.b == 0);
static assert(E1.c == 2);
static assert(E1.d == 2);
static assert(E1.e == 3);

enum E2
{
a,
b,
alias c = a,
d,
alias e = a,
f,
}

static assert(E2.a == 0);
static assert(E2.b == 1);
static assert(E2.c == 0);
static assert(E2.d == 2);
static assert(E2.e == 0);
static assert(E2.f == 3);

void main() { }